The present invention is related to a locking apparatus, and more particularly to an assembled/linked locking apparatus of a tool cabinet or file cabinet having several drawers.
A drawer and a cabinet are equipped with corresponding rails. The rails are slidably fitted with each other for easily pushing or drawing the drawer within the cabinet. The rails are provided with stoppers such as projecting blocks or projecting plates to prevent the drawer from detaching from the cabinet and dropping.
The drawer is often designed with a considerable length for receiving more articles. In order to fully draw the drawer out of the cabinet without being derailed and immediately push the drawer into the cabinet after taking articles, three rails are provided, including a cabinet slide rail, a middle slide rail and a drawer slide rail. Each slide rail has stop blocks on predetermined portions of one end or two ends of the slide rail. The slide rails are slidably assembled with each other and the stop blocks stop each other, whereby the drawer can be fully drawn out of the cabinet without derailing and dropping. Ball bearings are provided between the slide rails to reduce frictional force therebetween and noise.
The tool cabinet or file cabinet includes several drawers arranged from upper side to lower side. After the drawers contain tools or files, the drawers will have considerable weight. In the case that the drawers are drawn too hard or in the case of earthquake or collision by external force, the tool cabinet or file cabinet will be tilted to make some drawers slip out. Under such circumstance, the gravity center of the cabinet will change and the cabinet may fall down.
In order to avoid tilting down of the cabinet when drawing out too many drawers, a slide rail locking structure has been developed by which only one drawer can be drawn at one time. Substantially, a linking unit is disposed at one end of each slide rail assembly. Once the drawer slide rail of one slide rail assembly is pulled, the linking unit is activated to drive a link disposed between the respective slide rail assemblies to stop the drawer slide rails of other slider rail assemblies from being pulled. For example, in U.S. Pat. No. 5,352,030, a disc-like activating block is disposed at rear end of the drawer slide rail. In U.S. Pat. No. 5,634,701, an activating block having a slope is disposed at front end of one side of the drawer. In U.S. Pat. No. 5,988,778, an activating block is disposed at front end of the drawer slide rail.
In U.S. Pat. No. 5,352,030, a hook body is disposed at rear end of the drawer slide rail for hooking and pulling the disc-like activating block. This is strength-consuming and the components are likely to be worn. Therefore, the using life of the product is shortened.